A hung jury is a slang term for a hopelessly deadlocked jury in a criminal
case, in which a decision on guilt or innocence cannot be made. Usually
it means there is no unanimous verdict , although a couple of states don't
require a unanimous verdict to convict. A mistrial will be declared by
the judge in the case of a hung jury, and a new trial with a new jury is
required. However, the prosecutor can decide not to retry the case.

The definition of a hung jury varies by jurisdiction. A jury may be
counted a jury as hung if it failed to reach a verdict on any charge or
on any defendant. Some jurisdictions only count a hung jury if the jury
failed to reach a verdict on all counts or on all defendants. The number
of counts affects the likelihood of a hung jury. As the number of counts
increases, so does the opportunity for disagreement. So, the more counts,
the more likely that a jury will hang on at least one of them. Local law
should be consulted for the exact requirements for a hung jury in your
area.